The X pipe is installed in place of the rear cats and H pipe and flows dual pipes into the OEM resonator with single pipe afterwards to mufflerless exhaust tip. Resonator acts as a muffler but is less restrictive, but works very well with the sound enhancement in combo with the X pipe. No drone what-so-ever, till you goose it. Sorry, don't have an after pic but here's a before to give you the idea.

Cats and H out, X in and muffler out. Less back-pressure and a little leaner but eurotune takes care of all dat! No loss of torque.

I've also read where guys have removed only the cats and installed the X along with the H intact, but my thinking was you get better linear flow without the H.